U.S. design Pat. No. 268,683 issued Apr. 19, 1983 to the American Optical corporation (inventor: Dale TENNY) discloses an eyewear including a main frame, a pair of lenses carried spacedly from one another by the main frame, and a pair of ear stems projecting from and pivotally carried by the opposite lateral ends of the main frame. Each of the two lenses is toroidal, i.e. arcuate about both a vertical axis and a horizontal axis with different radii of curvature. The main frame includes an intermediate bridge part, separating the two lenses, with the bridge part being generally flat about at least the horizontal axis. The edges of each lens are completely circumscribed by the main frame.
U.S. utility Pat. No 4,867,550 issued Sep. 19, 1989 to Oakley, inc. (inventor: James JANNARD, hereafter patent JANNARD '550) discloses a unitary transparent lens for use in eyeglasses. The lens includes a first eye pane and a second eye pane, which are located directly in front of the wearer's right and left eyes, respectively, and are merged together with a unitary bridge portion. This single lens is premolded to be toroidal, with each of the vertical and horizontal axes having a different radius of curvature which creates a toroidal shape; these radii being each limited to a narrow range. The lens has a nose opening with an upper extremity, this upper extremity being positioned at a specified range from the upper edge of the lens. The lens portion passing above the upper extremity is a continuous surface defined by the same vertical and horizontal arcuate axes. JANNARD '550 also allegedly provide ventilation behind the lens, due to the ventilation gap formed between the lower edges of the eye panes and the wearer's face, while providing sufficient space between the eyes and the lens to avoid eyelash contact.
It is also known to provide a molded single plastic lens of non uniform thickness to try to decrease optical distortion.